How big a beam do I need?

Reply

  #1  
Old 03-22-07, 09:10 PM
Member
Thread Starter
Join Date: Mar 2007
Posts: 5
How big a beam do I need?

I know there are some enginerds around here. I want to build a loft at the back of the shop. It is 5 feet deep, and 25 feet wide. If at all possible I want to build it without any columns in the middle. What kind of beam would I need to support this thing across the front? I made a quick drawing with Google Sketchup to help. Just copy and paste into a browser window.

http://img221.imageshack.us/img221/3458/garageloftgm0.jpg


Is it possible?
 
Sponsored Links
  #2  
Old 03-23-07, 03:58 AM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Dec 2005
Location: USA
Posts: 39,968
Just a nail driver, but the span tables I refer to indicate you can build a glued laminated 2x4 beam with a height of 9 1/2" to span 28'. Now, LVL will be a little more expensive, but easier to handle. I would opt for the LVL. Transporting it will be a bear. You can site build the 2x4 glued laminated beam.
 
  #3  
Old 03-24-07, 09:35 AM
Member
Thread Starter
Join Date: Mar 2007
Posts: 5
Originally Posted by chandler View Post
Just a nail driver, but the span tables I refer to indicate you can build a glued laminated 2x4 beam with a height of 9 1/2" to span 28'. Now, LVL will be a little more expensive, but easier to handle. I would opt for the LVL. Transporting it will be a bear. You can site build the 2x4 glued laminated beam.
LVL? Is that an engineered beam? Not familiar with the term. I have a trailer and can transport it no problem. Maybe that would be the best thing to do. Any site you can point me to that would show me how to build a laminated beam? Making it from 2x4s Would it be 7 2x4s laid on top of each other with the ends staggered? That would make it 9 x 3.5 or so. Would it be better to build from larger stock, three 2x10s sandwiched together or something? Where can I find those span tables?
 
  #4  
Old 03-24-07, 11:32 AM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Dec 2005
Location: USA
Posts: 39,968
Sorry, LVL stands for laminated veneered lumber, and is manufactured using thin layers of wood glued and pressed under heat until it is cured. Be prepared, as you will need a 25' trailer to haul it on as it comes in one piece. Site building a laminated beam would make more sense, as you state, 7 glued and nailed 2x4's in a staggered pattern will make up the structural integrity in the span tables. Using a larger dimension lumber will only make it too heavy to handle, and its own added weight will have to be calculated into the total weight of the loft, so minimizing the lumber to what the span tables recommend would be in your best interests. I use the tables in a reference book I have in my office, but I just googled "live load span tables" and got several sites with good information.
 
  #5  
Old 03-24-07, 08:53 PM
Member
Thread Starter
Join Date: Mar 2007
Posts: 5
Originally Posted by chandler View Post
Sorry, LVL stands for laminated veneered lumber, and is manufactured using thin layers of wood glued and pressed under heat until it is cured. Be prepared, as you will need a 25' trailer to haul it on as it comes in one piece. Site building a laminated beam would make more sense, as you state, 7 glued and nailed 2x4's in a staggered pattern will make up the structural integrity in the span tables. Using a larger dimension lumber will only make it too heavy to handle, and its own added weight will have to be calculated into the total weight of the loft, so minimizing the lumber to what the span tables recommend would be in your best interests. I use the tables in a reference book I have in my office, but I just googled "live load span tables" and got several sites with good information.
Thanks. That gives me somewhere to start.
 
  #6  
Old 03-24-07, 09:15 PM
Member
Join Date: Aug 2000
Location: USA
Posts: 15,834
Any changes to structure require submitting plans to Building Code Office and getting permits and require submission of plans. Unless you live in the hinterlands where codes are not enforced, this is a requirement.
 
  #7  
Old 03-25-07, 11:31 AM
Member
Join Date: Sep 2000
Location: Tujunga, CA, USA
Posts: 209
Chandler,
Can you double check your span table for the 3-1/2" by 9-1/2" beam. I quickly punched some numbers into a calculator for deflection and it did not look good for a 28' span (I easily could have made a mistake). First, I was fairly liberal with a 40 psf total floor load (or 100 plf) and E = 2000 ksi; the deflection was about 2-3/4". With a little more conservative guesses of 50 psf and E = 1600 ksi, the deflection was over 4".

Notes:
psf - pounds per square foot
plf - pounds per linear foot
E - Modulus of Elasticity, a property of the material. Some times it is abbreviated so E 2.0 = 2000 ksi.
ksi - kips per square inch (kip = 1000 lbs)
 
  #8  
Old 03-25-07, 06:31 PM
Member
Thread Starter
Join Date: Mar 2007
Posts: 5
Originally Posted by Phil H View Post
Chandler,
Can you double check your span table for the 3-1/2" by 9-1/2" beam. I quickly punched some numbers into a calculator for deflection and it did not look good for a 28' span (I easily could have made a mistake). First, I was fairly liberal with a 40 psf total floor load (or 100 plf) and E = 2000 ksi; the deflection was about 2-3/4". With a little more conservative guesses of 50 psf and E = 1600 ksi, the deflection was over 4".

Notes:
psf - pounds per square foot
plf - pounds per linear foot
E - Modulus of Elasticity, a property of the material. Some times it is abbreviated so E 2.0 = 2000 ksi.
ksi - kips per square inch (kip = 1000 lbs)
Thanks for looking out! My span is 25 feet, so that may make a bit of difference.
 
  #9  
Old 03-25-07, 06:50 PM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Dec 2005
Location: USA
Posts: 39,968
PhilH, the tables I was consulting allowed 51 psf load and a span of 24', and a reduced 32 psf with a span of 28'. Now, I wouldn't recommend this to be the only support in the loft by any means. I still advocate the LVL, although unwieldy.
 
  #10  
Old 03-28-07, 06:13 PM
Member
Join Date: Mar 2007
Posts: 1
open joists

Correct me if I missed something but what are your building dimensions again?
25' x ? Make sure you aren't running the joists the wrong way, but if 25' is
the shortest run, you may want to look into open joists which are
incredibly strong.

Check out this link for span info:
http://www.ufpi.com/product/oj/prod/faq.htm
 
  #11  
Old 03-28-07, 09:23 PM
Member
Thread Starter
Join Date: Mar 2007
Posts: 5
Originally Posted by carouse2 View Post
Correct me if I missed something but what are your building dimensions again?
25' x ? Make sure you aren't running the joists the wrong way, but if 25' is
the shortest run, you may want to look into open joists which are
incredibly strong.

Check out this link for span info:
http://www.ufpi.com/product/oj/prod/faq.htm
25' long, 5' deep.

There is a link in my original post that will take you to a drawing of what I want.

Looking at the page you posted. Very interesting. Looks like for a 25' span I would need 14" tall open joists, though? I'm loosing a lot of space quick. With some sort of beam it looks like I can save a few inches.
 
  #12  
Old 02-12-09, 09:51 AM
Member
Join Date: Feb 2009
Posts: 1
Beam for Chandler

According to my "KeyBeam" software I use regularly, a quad 1-3/4x11-7/8 LVL will be adequate. This will give you an L/703 with a .42" of deflection. I set the loading to L/480 240 and 40 live 10 dead.
 
  #13  
Old 03-05-09, 01:09 PM
Member
Join Date: Feb 2009
Location: kansas
Posts: 26
Originally Posted by chandler View Post
Just a nail driver, but the span tables I refer to indicate you can build a glued laminated 2x4 beam with a height of 9 1/2" to span 28'. Now, LVL will be a little more expensive, but easier to handle. I would opt for the LVL. Transporting it will be a bear. You can site build the 2x4 glued laminated beam.
What kind of glue would you use on a this kind of beam? Construction adhesive? carpenters glue? Thanks
 
Reply


Thread Tools
Search this Thread
Display Modes
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -7. The time now is 11:05 PM.